Comment by chippiewill

> but many features are still only available in nightly rust.

Nope. The features are all in stable releases (Since last Spring in fact). However some of the features are still marked as unstable/experimental and have to be opted-in (so could in theory have breaking changes still). They're entirely features that are specific to kernel development and are only needed in the rust bindings layer to provide safe abstractions in a kernel environment.